Mechanisms in cancer pain

Abstract

Pain in the cancer patient is caused primarily by the development of the disease process (tumours, metastases), which in turn causes, amongst other things, infiltration of soft tissues, bones, nervous system structures, and serous membranes. Cancer may also cause necrosis of solid organs or induce the occlusion of blood vessels. In addition, pain in the cancer patient may be the consequence of anticancer therapy, which, in the case of radiation therapy, may lead to the development of post-radiation plexopathies or myelopathies. In the case of chemotherapy, related pain syndromes and peripheral neuropathy are the common adverse events of a number of anticancer medications. Surgically treated patients, especially those following thoracotomy, mastectomy, or amputation, may develop persistent postoperative pain (postsurgical neuropathy). An important kind of pain in cancer patients is acute pain associated with cancer pain treatment, which is due to both diagnostic (i.e., biopsies, blood samples) and therapeutic procedures (acute postoperative pain). Lastly, the pain in question may be due to mechanisms unrelated to the cancer itself or its treatment, e.g., chronic headache, low-back pain, and pain that the patient may have suffered prior to the diagnosis of cancer.